Apparatus for moulding articles from plastics material



Aug. 23, 1966 J. M. SCHNEIDER APPARATUS FOR MOULDING ARTICLES FROMPLASTICS fiATERIAL 8 Sheets-Sheet 1 Filed April 16, 1965 Aug. 23, 1966J. M. SCHNEIDER 3,267,523

APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL Filed April 16,1965 8 Sheets-Sheet 2 1966 J. M. SCHNEIDER 3,267,523

APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL Filed April 16,1965 8 Sheets-Sheet 3 Fig.3. y A [L 3 3, 1966 J. M SCHNEIDER 3,267523APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL 8 Sheets-Sheet 4Filed April 16, 1965 1966 J. M. SCHNEIDER 3,267,523

APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL Filed April 16,1965 8 Sheets-Sheet 5 Aug. 23, 1966 J. M. SCHNEIDER APPARATUS FORMOULDING ARTICLES FROM PLASTICS MATERIAL 8 Sheets-Sheet 6 Filed April16, 1965 23, 1966 J. M. SCHNEIDER 3,267,523

APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL Filed April 16,1965 8 Sheets-Sheet 7 k312i 12:1 I L? FzgJA. i /33 Aug. 23, 1966 J. M.SCHNEIDER APPARATUS FOR MOULDING ARTICLES FROM PLASTICS MATERIAL 8Sheets-Sheet 8 Filed April 16, 1965 a MS. 9 m3 Bu m Q6 m% \"2 ms 3 ME $6a E: 33 m2 umw ISM i 92 mm gffi m. mt m; @2 56} 32:: a 5m: wt

United States Patent 3,267,523 APPARATUS FOR MOULDIN G ARTICLES FROMPLASTICS MATERIAL Jack M. Schneider, Kingswood, lnrrey, England,assiguor to Calmec (Manufacturing) Limited Filed Apr. 16, 1965. Ser. No.448,595 Claims priority, application Great Britain, Apr. 22, 1964,16,731/64; Oct. 21, 1964, 42,903/64 9 Claims. (Cl. I8ll9) This inventionrelates to apparatus for forming articles from sheet plastics material.

According to the invention, apparatus for forming articles from sheetplastics material comprises two parallel arranged, relatively movableplatens respectively providing co-operating tool means adapted, when theplatens are disposed in their operative positions, to form an articlefrom a section of a sheet of hot plastics material disposed between theplatens, means for efiecting relative movement of the platens towardsone another, stop means having parts which engage when the platens reachtheir operative positions and serve to retain the platens in thesepositions against the action of the moving means, cutting means fixedlysecured to one of the platens, remotely of the stop means, and soarranged that the periphery of the sheet section is engaged fromopposite sides of the sheet by the cutting means and facing parts of theother platen, respectively when the platens are in their operativepositions, and means for causing the cutting means and the said facingparts to be urged together more strongly, whereby the inherentflexibility of a platen allows further, limited relative movementbetween the cutting means and the said facing parts sufiicient to causethe sheet to be out along at least a major part of the periphery of thesection.

Preferably, the cutting means are fixedly secured to a tool on the saidone platen with the cutting edges thereof projecting from the tooltowards the said facing parts.

In this event the cutting means may comprise cutting elements whichextend along the periphery of the said tool so that the sheet is outalong the whole of the periphery of the section.

The invention also includes a method of forming articles from sheetplastics materials, comprising disposing a section of a sheet of hotplastics material between two parallel arranged, relatively movableplatens so that the periphery of the section is engaged from oppositesides of the sheet by cutting means fixedly secured to one of theplatens and facing parts of the other platen, respectively, forming anarticle from the sheet section by co-operating tool means provided onthe platens, and urging the platens together more strongly whereby theinherent flexibility of the platens allows further, limited relativemovement between the cutting means and the said facing parts sufficientto cause the sheet to be cut along at least a major part of theperiphery of the section.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIGURE 1 is a side elevation of an extrusion apparatus and an apparatusaccording to the invention for forming articles from sheet plasticsmaterial supplied from the extrusion apparatus;

FIGURE 2 is a side elevation of the forming apparatus of FIGURE 1 withparts thereof shown in section;

FIGURE 3 is a section taken along the line IIIIII of FIGURE 2;

FIGURE 4 is a plan view, partly in section, of a carriage upon whicharticle forming tools of the forming apparatus of FIGURE 1 are mounted;

FIGURE 5 is a section taken along the line VV of FIGURE 3;

Patented August 23, 1966 FIGURE 6 is a perspective view of an articleforming tool and associated parts of the forming apparatus of FIGURE 1;

FIGURES 7A to 7E show, diagrammatically, successive stages in theforming of an article by the forming apparatus of FIGURE 1 and thedetaching of the formed article from the sheet;

FIGURE 8 shows diagrammatically the hydraulic circuit for controllingthe operations of the forming apparatus.

Referring to FIGURE 1 of the drawings, an apparatus 1 according to theinvention is for use with a conventional extruding apparatus 2 having aheating chamber, a hopper 3 for the supply of powdered plastics materialto an inlet of the heating chamber, and a screw for conveying heatedmaterial from the chamber and forcing the material through an extrudingdie at the outlet 4 of the apparatus to form a sheet 6. The extrudingapparatus 2 is mounted on a framework 7 with the extruding dies soarranged that the sheet 6 of extruded material is travelling downwardlyas it emerges from the outlet 4.

The apparatus 1 operates on successive sections of sheet 6 as theyemerge from the extrusion apparatus 2, tool means of the apparatus beingarranged to engage a section whilst it is still hot and form the sectionto the shape of an article whilst moving downwardly in engagement withthe section. After a predetermined interval of time sufficient for thesection to cool, knives fixedly secured relative to the tool meanseffect cropping of the formed article from the remainder of the sheet,whereupon the tool means are disengaged and return to their initialposition ready to operate on the succeeding section. The formed articleis ejected from an outlet passage 8 of the apparatus 1 whilst theremainder of the sheet is returned to an inlet 9 of a granulator 10 forreturn to the extrusion apparatus 2.

The sequence of operations is effected automatically by means of ahydraulic circuit (shown in FIGURE 8 and described hereinafter) whichincludes electrically operated control valves, part of the controlapparatus for the hydraulic circuit and the controls for the extrusionapparatus being located in a control cabinet 11 mounted along side andbeneath the extrusion apparatus 2.

Heated sheet 6 is travelling downward-1y as it emerges from theextrusion apparatus 2 and the apparatus 1 is therefore provided with anupright elongated supporting structure 12, which can be arranged beneaththe outlet 4 to define a downwardly extending path for the sheet. Thissupporting structure includes a substantial base 13 and a supportinghead 14 which is mounted on the base, immediately below the outlet 4 ofthe extrusion apparatus, by four upstanding pillars 16. The pillars 16are disposed at the corners of a rectangle, when the apparatus is viewedin plan (see FIGURE 4).

Referring to FIGURES 2 and 3, material emerging from the outlet 4 of theextrusion apparatus 2 is drawn downwardly through an aperture 17 in thesupporting head 14 by a pair of upper driving rollers 18 and 19,respectively, mounted in the head and arranged to engage opposite sidesrespectively of the sheet 6. The roller 19 is biassed horizontallytowards the roller 18 in the manner hereinafter described so that thesheet 6 is gripped firmly between the rollers. From the upper drivingrollers 18 and 19 a section of the sheet 6 travels downwardly throughthe space defined between the four supporting pillars 16, where anarticle is formed from the section, detached, and is then ejectedforwardly of the apparatus through the outlet passage 8 in the base 13.As shown in FIGURE 1, the remainder of the sheet travels between a pairof lower driving rollers 21 and 22, respectively, disposed one above theother in the base 13 of the structure, upwardly and rearwardly from therollers 21 and 22 to a engage a lower part of an idler roller 23,upwardly from the idler roller 23 to a driven roller 24, and finallydownwardly between roller 24 and a roller to the inlet 9 of thegranulator.

As shown in FIGURES 2 and 3 of the drawings, the head 14 of thesupporting structure comprises a top plate 26 which is mounted on theupper ends of the pillars 16 and in which is formed the central,rectangular aperture -17 for the sheet of extruded material. Side plates27 of the head 14 extend downwardly from the top plate 26, on opposedsides of the sheet 6, respectively, and these plates provide support forthe upperdriving rollers 18 and 19, driving elements associated withthese rollers, and means for adjusting the horizontal location of theroller 19.

The upper driving rollers 18 and 19 are mounted on parallel shafts 28and 29, respectively, which extend between the side plates 27 of thehead and are journalled in bearings supported by the side plates. Thehousings 31 of the bearings which support the shaft 28 are fixedlysecured relative to respective side plates 27 and are so arranged thatthe rearrnost portion of the roller .18 contacts the front surface ofthe sheet 6 of plastics material. Housings 32 of the bearings for shaft29 .are mounted in horizontally extending apertures formed in respectiveblocks 33 on the outer surfaces of the side plates 27, the housings 32and blocks 33 being formed with engaging tongues and grooves whichpermit relative horizontal movement therebetween. Adjustment of thehousings 32 in the blocks 33 is efiected by air pressure operateddevices each of which comprises an air cylinder 34 secured to a sideplate 27 of the head 14 and piston rod 35 connected to the housing. Thecylinders-34 are provided with conduits 36 for the supply thereto of airunder pressure.

The location of the blocks 33 relative to the side plates 27 is adjustedso as to ensure that .a minimum spacing slightly less than the thicknessof the sheet emerging from the outlet 4 of the extrusion apparatus 2 isprovided between the rollers 18 and 19.

Each of these driving rollers 18 and 19 and their supporting shafts 28and 29, respectively, is hollow and a universal junction 37 is providedat each end of each of the shafts. Pipes 38 are connected to thejunctions 37 for supplying heated oil to the driving rollers, forpurposes hereinafter described.

The base 13 of the supporting structure comprises an upper plate 39 uponwhich the pillars are mounted and in which there is provided an aperture41 for the passage of sheet from which articles have been formed. Upperplate 39 is supported upon a ground-engaging plate 42 by means ofpillars 43.

Disposed between the plates 39 and 42 of the base 13 of the supportingstructure are the two lower driving rollers 21 and 22, arranged oneabove the other beneath the aperture in the plate 39. The drivingrollers 21 and 22 are mounted on parallel shafts 43 and 44,respectively, which extend transversely of the structure and arejournalled in bearings at their ends. The housings 45 of the bearingsfor the shaft 44 are mounted on brackets which depend from the upperplate 39 of the base 13 and are fixedly secured relative to that plate.The housings 46 of the bearings for the shaft 4-3 are mounted onrespective arms 47, however, each arm being pivo-tally mounted at itsend remote from the housing on a block 48 which is mounted on theground-engaging plate. Pivotal movement of the arms 47 causessubstantially vertical movement of the shaft 43 and roller 21, towardsand away from the shaft 44 and roller 22. Adjustment of the position ofthe shaft 43 is effected by means of air pressure opera-ted devicesprovided at opposed ends, respectively of the shaft, each deviceincluding an air cylinder 49 which depends from the upper plate 39 and amovable piston rod 51 which is secured at its end remote from thecylinder to one of the arms 47.

For driving the upper driving rollers 18 and 19 and the lower drivingrollers 21 and 22 endless duplex chains 52 and 53 are provided onopposed sides, respectively, of the supporting structure 12, each chainhaving an upper run within the head 14 of the supporting structure, alower run which extends into the base 13, and upward and downward runswhich extend between the base and the head.

Within its upper run the chain 52 travels from front to rear of theapparatus, i.e. from right to left as viewed in FIGURE 2 of thedraw'mgs. Thus, from an idler sprocket wheel 54 at the front of theapparatus the chain 52 initially passes upwardly over a sprocket wheel55 on the shaft 28 of driving roller 18, downwardly from sprocket wheel55 to engage a lower part of idler sprocket wheel 56, and finally,rearwardly to idler sprocket wheel 57 to begin its downward run. Chain53 travels from the rear to the front of the apparatus, i.e. from leftto right as viewed in FIGURE 2, during its upper run, the chain passingupwardly from idler sprocket wheel 58, over a sprocket wheel 59 on theshaft 29 of driving roller 19, downwardly to idler sprocket wheel 61 andfinally across to idler sprocket wheel 62. Idler sprocket wheels 54, 5eand 58 are mounted on one side plate 27 of the head and idler sprocketwheels 58, 61 and 62 on the other side plate 27.

During its lower run the chain 52 travels from rear to front of theapparatus 1, the run extending downwardly and forwardly from an idlersprocket wheel 63, which is mounted on an upstanding bracket 64 on upperplate 39 of the base, to engage a sprocket wheel 65 on the shaft 44,beneath an idler sprocket wheel 66 On bracket 67 which depends fromplate 39, and, finally, upwardly to idler sprocket wheel 68 on bracket69. Chain 53 travels rearwardly and downwardly from idler sprocket wheel71 on upstanding bracket 72 at the front of the apparatus to engage alower part of sprocket wheel '73 on shaft 44 and then upwardly fromsprocket wheel 73 to idler sprocket wheel 74 on a bracket 75 at the rearof the apparatus.

During its upward run the chain 52 passes directly from idler sprocketwheel 68 in the base 13 of the structure to idler sprocket wheel 54 inthe head 14 and chain 53 directly from idler sprocket wheel 74 tosprocket wheel 58. During their downward runs, however, the chains 52and 53 engage respective unidirectional clutch mechanisms 76 which aresecured relative to the tool means of the apparatus and are provided forpurposes hereinafter described.

The linear speeds of travel of the chains 52 and 53 are equal to oneanother and to the peripheral speeds of the upper driving rollers 18 and19 and the lower driving rollers 21 and 22, which in turn determine thespeed of travel of the sheet 6. Accordingly, it will be appreciated thatduring the major part of their downward runs the chains are movingparallel with and at the same speed as the downwardly moving sheet.

Referring now to FIGURE 1, the chains 52 and 53 are driven by means ofan electric motor 78 having a worm gear 79 coupled to the output shaftthereof and mounted in the base 13 of the structure. Drive istransmitted from a sprocket wheel 81 on an output shaft of the worm gear7 9 to a sprocket wheel 82 on the shaft 44 of driving roller 22 by meansof an endless chain 83. Driving roller 24 is also driven at the sameperipheral speed as the driving roller 22 by means of a chain 84 whichengages a sprocket wheel secured to the roller shaft and a furthersprocket wheel on the output shaft of the worm gear 79. Driving roller24 and the idler roller 25 associated therewith are provided with knifeblades which extend normally to the axes of the rollers and cut thematerial into longitudinally nd ng strips as it passes between them tothe inlet 9' of the extrusion apparatus 2.

The tools for forming an article from a section of an extruded sheet andknives for detaching an article from the remainder of the sheet aremounted on a carriage 85 which is movable upwardly and downwardlyrelative to the supporting structure 12. This carriage includes fourupright cylinders 86 each of which embraces a section of a pillar 16 ofthe structure and is of length approximately equal to one-half theheight of the pillar.

Referring to FIGURE 2 of the drawings, a piston 87 is secured to acentral section of each ofa first pair of diagonally opposed pillars 16and is disposed Within the upright cylinder 86 associated with thepillar so as to divide the cylinder into upper and lower chambers 88 and89, respectively. The upper part of each of this first pair of pillars16 is formed with an axially extending passage 91 which is connected toan inlet pipe 92 on the head 14 of the structure by means of a passage93 in top plate 26 and is connected to the interior of the upper chamber88 of the associated cylinder 86 by means of radial ports 94 close tothe piston 87. A further axial passage 95 is formed in the lower part ofeach of this pair of pillars 16 and communicates with an inlet pipe (notshown in the drawings) via a passage 96 in the upper plate 39 of thebase and with the interior of the lower chamber 89 of the cylinder viaports 97.

Supply of liquid under pressure to the upper chambers 88 via passages 92and 93 and withdrawal of liquid from the lower chambers 89 via passages95 and 96 causes the cylinders 86, and hence the carriage 85, to bemoved upwardly relative to the supporting structure 12 whilst supply ofliquid to the lower chambers 89 and withdrawal from the upper chambers88 effects downwards movement of the carriage.

In FIGURE 2 of the drawings the carriage 85 is just approaching itsuppermost position and a central section 98 of a lower end closure 99 ofeach of this first pair of cylinders 86 extends above the radial ports97. Communication between these ports and the lower chamber 89 of thecylinder 86 is then restricted to a narrow channel 101 in this centralsection of the end closure and the rate of exhaust of liquid from thechamber is reduced. The carriage is therefore de-celerated so that thelower end closure 99 of the cylinder does not impinge against the piston87 with too much force.

Narrow channels 102 in upper end closures 103 of the first pair ofcylinders 86 ensure that a similar de-celerating effect is produced whenthe carriage approaches its lowermost position.

Each of the other pair of diagonally opposed pillars 16 of thesupporting structure 12 is formed with an axial passage 104 whichextends upwardly from the upper plate 39 of the base 13 to radial ports105 which open into the cylinder 86 associated with that pillar. Liquidunder pressure is supplied to this other pair of cylinders 86 viarespective inlets 106 and passages 107 in the upper plate 39- and axialpassages 104 and radial ports 105 in the pillars 16. From this pair ofcylinders liquid is supplied via pipes (not shown in the drawings) tohydraulic mechanisms on the carriage 85 for operating the tools andknives in the manner hereinafter described.

On each side of the carriage 85 is an upstanding side plate 108 which issecured to the two cylinders 86 on that side of the structure 12. Asindicated in FIGURES 2 and 4, each side plate 108 is fixedly secured toa cylinder 86 disposed rearwardly of the sheet by means of a pair ofbrackets 109 and is secured to a cylinder disposed forwardly of thesheet by respective trunnions 111. The carriage 85 can therefore rotateslightly about a horizontal axis parallel with the plane of the sheet 6when it is subjected to large forces during operation of the tools.

Mounted on each side plate 108 are two idler sprocket wheels 112, whichare disposed vertically one above the other, and one of theunidirectional clutch mechanisms 76 which is disposed at a verticallocation intermediate those of the sprocket wheels 112 and is spacedhorizontally therefrom. During its downward run each chain engages thetwo idler sprocket wheels 112 which are disposed on 8 the same side ofthe apparatus as the chain and in travelling from one sprocket wheel tothe other engages a major portion of a sprocket wheel 113 on theunidirec tional clutch mechanism 76.

When the carriage is moving downwardly the clutch mechanisms 76 areengaged and serve to prevent the speed of the carriage from exceedingthat of the chains 52 and 53, i.e. the speed of movement of the sheet 6.During upward movement of the carriage 85 the clutch mechanisms 76 aredisengaged, however, and the carriage can be returned rapidly to itsuppermost position.

At the front and rear of the carriage and extending between its sideplates 108 are pairs of parallel arranged, horizontal supporting plates114 (see FIGURE 5) and between the pair of plates 114 at the front andrear of the carriage are mounted cylinders 115 and 116, respectively, ofhydraulically operated devices. Rectangular platens 117 and 118 aremounted on piston rods 119 and 120, respectively, of these hydraulicdevices, the platens being upright and disposed on opposed sides of thesheet 6, respectively.

Referring to FIGURES 3 to 6, mounted on the side of each of the platens117 and 118 which is remote from the sheet 6 are two guide blocks 122,each disposed midway between the upper and lower edges of the platen andclose to an upright side edge thereof. A horizontally extending recessis formed in each guide block 122 and the upper and lower faces of therecess are formed with grooves which engage a guide element 123 securedto a side plate 188 of the carriage 85.

Operation of the abovementioned hydraulically operated devices causesrelative movement between cylinders 115 and 116 and respective pistonrods 119 and 120 upon which the platens are mounted and engagementbetween guide blocks 122 and respective guide element 123 serves toensure that this movement is restricted to directions normal to theplane of the sheet material. Two stop elements 124 are secured to eachside plate 108 of the carriage and serve to limit advance of the platenstowards the sheet, as hereinafter described.

Secured to the inwardly facing side of each of the platens 117, 118 is atool for use in forming an article from a section of the sheet 6 of hotplastics material. The tool 125 which is provided on the platen 118disposed rearwardly of the sheet 6 has an operative face which issubstantially flat but is formed with apertures 126 and passages 127through which gas under pressure may be applied to the rear face of thesheet. The operative face of the tool 128 on the forwardly disposedplaten 117, however, is formed with recesses 129 to shape correspondingto the shape of the article or articles, to be formed from the sheet. Inthe present instance four open-topped containers each having arectangular base and rectangular side walls are to be formed from asingle section of sheet and the forward tool is therefore formed withfour recesses 129. Passages 131 communicate with four openings 132 atrespective bottom corners of each recess so that a reduced pressure maybe provided on the forwardly facing side of the sheet 6.

For detaching an article from the sheet at the end of a formingoperation the forward tool 128 is also provided with cutting means inthe form of knives which extend along the periphery of articles to becut from the section of sheet material between the tools (see FIGURES 5to 7). In the present case, where four separate articles are to bedetached .at the end of a forming operation, four main knife blades 133are secured to respective sides of the tool so as to form a rectanglewhen viewed from the rear of the apparatus. Additional knife blades 134and 135 extend parallel with horizontal and vertical pairs of knifeblades 133, respectively, and each defines the boundary between anadjacent pair of articles.

The knives 133 and 134 and 135 are all fixedly secured to the tool 128on the forward platen 17, and hence are fixed relative to the platenitself. Each knife is arranged 47 With its cutting edge projectingrearwardly of the tool face by a distance equal to 1 /2 times thethickness of the material which is being formed, i.e. for material of0.010 inch in thickness the knives project 0.015 inch.

Close to each of the four corners of each platen is a threaded aperturewhich extends through the platen and engaged in these apertures arerespective stop screws 136. Each stop screw is provided with a lockingnut 137.

The four stop screws 136 of the rearward platen 118 extend forwardlythrough the platen and in use of the apparatus are adjusted so thattheir forward ends engage respective stop elements 124 on side plates1118 of the carriage when the operative face of the tool 125 justtouches the rear surface of the sheet 6.

The stop screws 136 on the forward platen 117 project rearwar dlythereof and engage respective stop elements 124 when the knives 133, 134and 135 just touch the front surface of the sheet.

Mounted on the upper of the two supporting plates 114 at the front andrear of the carriage are respective switches 138 and 139 andde-celeration valves 141 and 142, see FIGURE 4, andassociated with theswitches are respective actuating rods 143 and 144 which extendsparallel with the direction of movement of the platens on the carriage.The end of each rod which is remote from the associated platen 117 or118 is of enlarged diameter and is arranged to engage and operate theassociated switch when the platen is moved inwardly towards the sheetand the tool thereon is about to engage the sheet. Actuation of a switch138 or 135 in this manner eifects operation of the associatedde-celeration valve 141 and 142 which causes de-celeration of the platenin the manner hereinafter described.

When the carriage 85 has completed its downward movement relative to thesupporting structure 12 and an article has been formed by the tools 125and 128 and detached by the knives 133, 134 and 135, the article isejected from the outlet passage 8 in the base 13 of the structure by ablast of air. This air is supplied through a pipe connected to the fronttool 128 but not shown in the drawmgs.

For effecting upwards and downwards movement of the carriage 85,movement of the tools 125 and 128 into and out of engagement with asheet section, and operation of the knives 133, 134 and 135 fordetaching a formed article from the sheet, the apparatus is providedwith a hydraulic circuit including control valves which are electricallyoperated. Microswitches are mounted on the supporting structure 12 so asto be engaged by the carriage and effect operation of the variousvalves, and hence the carrying out of the various operations performedby the apparatus sequentially and in a predetermined time relationship.

In this circuit, which is shown in FIGURE 8 of the drawings, liquidunder pressure for raising and lowering the carriage 85 is supplied froma tank by means of a double-pump 143, and liquid under pressure formoving the tools 125 and 128 is supplied from a second double pump 150.Both pumps are driven by an electric motor 144.

150. Both pumps are driven by an electric motor 144.

The pump 143 has two outlets 145 and 146 for supplying liquid to a mainsupply line 147, at rates equal to 8 and 50 gallons per minute,respectively. Outlet 145 of the pump is connected directly to the line147 but outlet 146 is connected to the line via a one way check valveCV2 and is also connected to tank via a pilot-operated unloading valveUV2. Operation of unloading valve UV2 is controlled by a liquid in apilot line 148 which extends from an outlet 162 of pump 150, via a flowcontrol valve FC2 and a solenoid operated four-way valve V4 to the valveUV2, and then from valve UV2 to tank via the valve V4.

Main supply line 147 is connected to a first inlet of asolenoid-operated valve V3 which has a first outlet thereof connected totank by means of a line 149, and second and third outlets connected tolines 151 and 152, respectively. A one-way check valve CV6 which is inparallel with a pilot operated stop valve 8V3 connects the line 151 tothe inlet pipe 92 on the head 14 of the supporting structure and thencevia passage 93 and passages 91 to the upper chamber 38 of each of thefirst pair of diagonally opposed cylinders of the carriage 85,designated 86A and 86B, respectively, in FIGURE 8. Line 152 is connectedto the lower chamber 89 of each of the cylinders 86A and 865 by means ofa parallel circuit consisting of a one-way check valve CV3 and a flowcontrol valve FC1, passage 96 in the upper plate 39 of the base of thesupportin structure and a passage 95 in the associated pillar 16.

Pressure relief valves RV2 and RVS are connected between lines 147 and152, respectively, an tank.

Operation of the hydraulic circuit to effect raising and lowering of thecarriage $5 relative to the supporting structure 12 takes place asfollows.

As the carriage 85 approaches its lowermost position on the structurethe outlet 14:: of pump 143 is connected to tank by the unloading valveUV2 and liquid is being supplied from the outlet 145 to the lowerchambers 89 of the cylinders 86A and via line 147, valve V3 and flowcontrol valve FC1. Upon reaching its lowermost position the carriageengages a first microswitch which is mounted on the supporting structureand controls the operation of solenoid operated valves V3 and V4, thespool of each valve being moved to the left of the position shown inFIGURE 8.

The outlet 145 of pump 143 is therefore connected to the upper chambers88 by means of line 147, valve V3, line 151 and one-way check valve CV6and liquid is supplied to these chambers at a rate of 8 gallons perminute. Liquid flows out from the chambers 89 to tank, via check valveCV3 and valve V3, at a corresponding rate and the carriage 85 thereforebegins to rise slowly. Operation of valve V4 allows liquid to flow inpilot line 148, at a rate determined by the setting of flow controlvalve FCZ, and, accordingly, at a predetermined time after the beginningof the upward movement of the carriage the unloading valve UV2 isoperated and outlet 146 of the pump 143 is disconnected from the tank.Liquid is then supplied from outlet 146 through check valve CV2 to theline 147, and hence to chambers 88, at a rate of 50 gallons per minute,Causing the carriage to rise rapidly.

Shortly before reaching its uppermost position the carriage 85 engages asecond microswitch on the supporting structure, which causes valve V4 tobe returned to the position shown in FIGURE 8, whereupon unloading valveUV2 operates to connect outlet 146 to tank again. Liquid is now suppliedto chamber 88 from the outlet 145 only, so that the rate of ascent onthe carriage is decreased. At the same time a further deceleratingeffect is produced by means of narrow channels 101 in the lower endclosures of the cylinders 86A and 8513, as described above.

Upon reaching its uppermost position the carriage 85 effects operationof a third microswitch which operates solenoids respectively associatedwith valves V3 and V4, causing V3 to move to the right from the positionshown in FIGURE 8 and V4 to move to a position in which liquid can flowin pilot line 148. With the valve V3 in this position liquid underpressure is supplied from the outlet 145 of pump 143- to the lowerchambers 89, via line 152, flow control valve FC1 and passage 96, at arate determined by the setting of FC1. A pressure is therefore exertedon the liquid in the upper chambers 88 and this pressure is transmittedvia passage 93 to pilot line 153, causing stop valve 5V3 to open. Liquidcan now flow from the upper chambers 88 to tank, via valves 8V3 and V3,and the carriage begins to descend. Moreover, after a predeterminedinterval, determined by the setting of the flow control valve FC2,unloading valve UV2 operates to disconnect outlet 146 of pump 143 fromthe tank and 9 liquid is then supplied from both outlets 145 and 146 tothe chambers 89.

It will be appreciated that the maximum rate at which liquid can besupplied to the lower chambers 89, determined by flow control valve FC1,is arranged to be sulficient to cause the carriage 85 to descend at aslightly faster speed than the speed of travel of the sheet 6 ofplastics material. However, as explained above, the engagement ofunidirectional clutch mechanisms 76 with respective chains 52 and 53serves to ensure that the carriage 85 moves downwardly as the same speedas the sheet.

When the carriage approaches its lowermost position at the end of aforming operation a fourth microswitch is engaged, causing operation ofvalves V4 and UV2 to decelerate the carriage. The above cycle ofcarriage movements is then repeated.

The pump 156 has two outlets 161 and 162 for supplying liquid to a mainsupply line 163 at rates respectively equal to 35 and 8 gallons perminute. Outlets 161 and 162 are connected to the line 163 by respectiveone-way check valves CV1 and CV4, and outlet 161 is also connected totank via a pilot operated unloading valve UV1 and a heat exchanger HE.Operation of unloading valve UV1 is controlled by liquid in a pilot line164 which extends from the outlet 162 of the pump 15% via asolenoidoperated four-way valve V5 to tank.

The main supply line 163 is connected to a first inlet of asolenoid-operated valve V1 which has a first outlet thereof connected byline 165 to one of the second pair of diagonally opposed cylinders 86,designated 86C in FIGURE 8, and a second outlet connected by line 166 tothe second of this pair of cylinders, designated 86D. A third outlet ofthe valve V1 is connected to a solenoid operated valve V2 by means of aline 167, the valve V2 having one outlet connected by line 168 to theline 166 and a second outlet connected by line 169 and the heatexchanger HE to tank.

A pressure relief valve RVl is connected to main supply line 163 and isadapted to connect this line to tank via the heat exchanger HE if thepressure in the line ex-, ceeds approximately 2000 lbs. per square inch.If the pressure is below this value the valve RV1 connects the line 163via a line 171 to an inlet of a solenoid operated valve V6 which has anoutlet connected to tank by a second relief valve RV4. Valve RV4 is setto open at a pressure of from 80 to 200 lbs. per square inch.

From the cylinder 86D liquid is supplied directly along a line 172 tothe cylinder 116 of the hydraulic device which is disposed at the rearend of the carriage 85, line 172 being connected to the side of thepiston remote from piston rod 120, platen 118 and tool 125 mountedthereon. This cylinder 86D is also connected by means of a parallelcircuit, consisting of a one-way check valve CV7 and a pilot operatedstop valve SV2, and a line 173 to the cylinder 115 of the hydraulicdevice at the front of the carriage, line 173 being connected to theside of the piston remote from piston rod 119, platen 117 and tool 128.

The cylinder 86C is connected by means of a. line 174, a parallelcircuit comprising a pressure control valve PCVl, the mechanicallyoperated deceleration valve 142, mentioned above, and a one-way checkvalve CV8, to a line 175, which in turn is connected to the chamber incylinder 116 through which the piston rod 120 extends. Line 174 alsoconnects the cylinder 86C to the cylinder 115 via a parallel circuitconsisting of stop valve SV4 and check valve CV9, a parallel circuitcomprising a pressure control valve PCV2, the mechanically operatedde-celeration valve 141, mentioned above, and one-way check valve CV10,and a line 176. Pressure control valves PCVl and PCVZ are connected to apilot line 177 which extends via the solenoid-operated valve V5 to tank.

Operation of the hydraulic circuit to effect movement of the platens 117and 118 and their associated tools 128 and 125, respectively, relativeto the carriage 85 and the 10 cropping of formed articles from the sheet6 by knives 133, 134 and 135 is carried out as follows.

As the carriage begins its downward movement from the top of thesupporting structure 12 it engages a fifth microswitch which causesoperation of a solenoid controlling the valve V1, moving the spool ofthis valve to the right from the position shown in FIGURE 8. Unloadingvalve UV1 is closed and liquid under pressure is therefore supplied fromboth outlets 161 and 162 to the line 163, and through the valve V1 toline 166 and the cylinder 86D. Valve V6 is open so that the pressure inline 163 is determined by the setting of relief valve RV4, i.e. 80 to200 lbs. per square inch. From the cylinder 86D liquid flows directlyalong line 172 to the cylinder 116 but is prevented from reachingcylinder by the check valve CV7 and stop valve 8V2. Liquid flows outfrom the cylinder 116 via line 175, valve PCVl, line 174, the cylinder86C, valve V1, line 167, valve V2, line 169 and heat exchanger HE totank. The piston in cylinder 116 is therefore moved from left to rightin FIGURE 8, causing the platen 118 and tool to advance towards thesheet 6.

After the platen 118 has moved through a predetermined distance itoperates a sixth microswitch which is mounted on the carriage 85 andupon operation energises the solenoid associated with valve V2, movingthe spool of this valve upwardly from the position shown in FIG- URE 8.Line 167 is therefore connected directly to the line 168, and thence toline 166, the cylinder 86D and line 172 so that liquid leaving one sideof the piston in cylinder 116 is fed round to the other side as anaddition to liquid supplied to this other side from pump 150. The pistonin cylinder 116, piston rod 120, platen 118 and tool 125 are thereforeadvanced rapidly towards the sheet 6.

When the platen 118 is a predetermined distance from the sheet a seventhmicroswitch on the cariage 85 is op erated by the platen, causing valveV2 to be returned to the position shown in FIGURE 8 and valve V5 tobemoved to the right from the position shown in the figure. The movementof valve V2 prevents liquid flow from line 167 to 168, reducing the flowof liquid along line 166 to that supplied from the pump 150. Themovement of V5 operates unloading valve UV1 to connect outlet 161 of thepump 143 to tank, thereby reducing the volume of liquid supplied alongline 166 from the pump 150, and in addition allows a flow of liquid totank along line 177, thereby causing pilot control valve PCVl to close.These three changes all serve to decelerate the inwards movement of theplaten 118 and its tool 125. Moreover, flow of liquid from the cylinder116 along line 175 to line 174 must now pass through deceleration valve142 which, as described above, is operated to cause a final decelerationjust before the platen 118 reaches its operative position in which thestop screws 136 on the platen 118 cugage respective stop elements 124 onthe carriage and the front face of tool 125 just touches the rearsurface of sheet 6.

As the platen 118 reaches its operative position an eighth microswitchon the carriage 85 is operated by the platen and causes operation ofvalve V5 to disconnect line 177 from tank and effect operation ofunloading valve UV1, thereby disconnecting the outlet 161 of pump fromtank.

Since the piston in cylinder 116 has reached the limit of its movementtowards the sheet 6 the supply of liquid along line 172 causes anincreased pressure to build up in this line, and hence in pilot line178. Pressure in line 178 causes the valve SVZ to open so that liquidcan now flow from the cylinder 86D along line 173 to the cylinder 115 atthe front of the carriage 85. The piston, piston rod 119, platen 117 andtool 128 associated with this cylinder are now moved inwards by means ofa similar sequence of valve operations to that described in connectionwith cylinder 116, inward movement being 11 complete when the stopscrews 136 on the platen 117 engage respective stop elements 124 andknives 133, 134 and 135 on the tool 128 just touch the front surface ofthe sheet'6.

As the carriage 85 moves down with a section of the sheet 6 engagedbetween the tool 125 and the knives 133, 134- and 135 on the tool 128, aninth microswitch is operated by the carriage and causes a vacuum pumpto be connected to the passage 131, openings 132 and the interior ofrecesses 129 of tool 128, and a tenth microswitch to be operated andcause air to be blown through passages 127 and openings 126 on to therear face of the sheet. The section of sheet between the tools 125 and128 is therefore drawn forwardly so that parts thereof enter respectiverecesses 129 in the tool 128 and assume the shape of these recesses.

After a further predetermined interval of time sufficient for theengaged sheet section to have become cooled, the downwardly movingcarriage operates an eleventh microswitch on the supporting structurewith causes momentary operation of valve V6 to close relief valve RV4.The pressure in line 171, and hence the pressure in lines 163, 166, 172and 173, can therefore rise to a valve determined by the setting ofrelief valve RV1, i,e. approximately 2000 lbs. per square inch.

The increased pressure in lines 172 and 173 is transmitted to the liquidin respective cylinders 115 and 116 and to the pistons therein, causingthe tools 128 and 125 to be urged into engagement with the sheet by agreatly increased force. The corner of each platen 117 and 118 is, ofcourse, prevented from further movement towards the sheet by engagementto stop screws 136 with respective stop elements 124. However, theincreased force which is now applied to the central part of each platenand the inherent flexibility of the material of each platen are suchthat these central parts are caused to move a few thousandths of an inchcloser together. In so doing the knives 133, 134 and 135 on the platen128 pierce the sheet 6 to detach the four formed articles therefrom.

Immediately after this cutting operation the downwardly moving carriageoperates a twelfth microswitch which causes the valve V1 to be moved tothe left of the position shown in FIGURE 8. Liquid under pressure is nowsupplied from outlets 161 and 162 of the pump 150 via line 163, valve V1and line 165 to the cylinder 86C. From this cylinder the liquid flowsalong line 174 and through check valve CV8 and line 175 to the cylinder116 but is prevented from reaching cylinder 115 by the check valve CV9and stop valve SC4. At the same time liquid can flow from the other sideof the piston in cylinder 116 to tank via line 172, the cylinder 86D,line 166, valve V1, line 167, valve V2, line 129 and heat exchanger HE.The piston in the cylinder 116 therefore moves so that the platen 118and tool 125 are moved rearwardly of the carriage 85, away from thesheet 6.

Whenthe position in cylinder 116 and the associated piston rod 120,platen 118 and tool 125 have reached their rearward position thepressure in the chamber on side of the piston through which the rod 120extends increases and this increase in pressure is transmitted via line175 to line 174, and hence the pilot line 179, causing valve SV4 toopen. Liquid under pressure can now flow from line 174 through the valveSV4, check valve CV10, and line 176 to the cylinder 115 and the platen117 and tool 128 associated with this cylinder are moved forwardly awayfrom the sheet 6 in a similar manner to that described for platen 118and tool 125.

When the platen 11-8 and tool 125 have reached their forward positionthe platen causes operation of a thirteenth microswitch, which causesair to be blown along passage 131 and openings 132 in the tool 128. Thefour formed articles are therefore blown from the tool 128 and fallthrough an aperture in the upper plate 32 of the base of the structureand emerge from the outlet 8. The cycle of operations can then berepeated.

approaching respective stop elements 124.

1.2 With the apparatus out of use the carriage is, of course, in itslowest position. i

To commence operations the heaters of the extrusion apparatus 2 areturned on and powdered plastics material is supplied to the inletthereof via the inlet hopper 3. The valves V1 and V3 of the hydrauliccircuit shown in FIGURE 8 are moved into the positions shown in thisfigure, so that the outlets 161 and 162 of pump 150 and the outlets 145and 146 of pump 143 are connected to tank and the electric motor 144 isswitched on.

When the extrusion apparatus 2 is working, sheet extruded from itsoutlet is arranged so that it travels downwardly between the upperdriving rollers 18 and 19 of the apparatus 1, through the space definedby the four pillars 86 of the supporting structure 1 2, between thelower driving rollers 21 and 22, and then via the rollers 23, 24- and 25to the inlet 9. The motor 78 in the base of the apparatus is switched onso that the roller 24 and the lower driving rollers 21 and 22 arerotated and drive is transmitted via the chains 52 and 53 to the upperdriving rollers 18 and 19. The speed of rotation of the upper drivingrollers 18 and 19 is adjusted by varying the speed of motor 78 and thespacing of these rollers adjusted by means of the air pressure operateddevices comprising respective cylinders 34 and piston rods 35, theadjustments being such that sheet is drawn downwardly from the outlet 4-at a rate which, in accordance with the rate at which material is beingextruded, produces the desired sheet thickness.

With the sheet being extruded from outlet 4 and travelling down thesupporting structure 12 properly the valve V3 is moved to the left fromthe position shown in FIGURE 8 of the drawings and the carriage 85begins to ascend, first slowly, then rapidly, and finally again slowly,in the manner described above. Upon reaching the top of the structurethe carriage begins to descend, first slowly and then at a rate equal tothe rate of downward travel of the sheet, as described, and then engagesthe fifth microswitch which sets in motion the above mentioned sequenceof platen movements.

FIGURES 7A to 7B show, diagrammatically successive stages in the formingof articles and the cutting of the formed articles from the sheet 6. InFIGURE 7A the stop screws 136 on the rear platen 118 have alreadyengaged respective stop elements 124, so that the tool 125 is in contactwith the rear surface of the sheet 6, and the stop screws 136 on thefront platen 1 17 are just FIGURE 7B shows the stop screws 136 on thefront platen 117 in their engaged positions, with the knives 133, 1 34and 135 just contacting the front surface of the sheet, and it is atthis stage that forming takes place, the sheet being drawn forwardlyinto the recesses 129 of the tool 128, as shown in FIGURE 7C. FIGURES 7Dand 7E both show the apparatus at the moment when an increased pressurehas been applied to the cylinders and 116, urging the platens 1 17 and118 more strongly together and causing the knives 133, 134 and 135 toengage the front face of tool and in so doing pierce the sheet 6.

Immediately after this cutting operation the carriage 85 operates thetwelfth microswitch and sets in motion the above described sequence ofoperations involving withdrawing the rear platen 118 and forward platen117 from the sheet and ejecting the formed articles from the recesses129. The carriage 85 is then decelerated, stops, and commences itsreturn, upward movement as described.

In order to prevent wastage of sheet material the return, upwardmovement of the carriage 85 is made as rapid as possible relative to thespeed of downwards movement so that the amount of sheet material betweensuccessive sections engaged by the tools 125 and 128 is a minimum.Preferably the time during which a section of the sheet is engaged bythe tool-s for forming and cutting is such that the vertical location ofthe upper edge of the section at disengagement of the tools is justabove the original vertical location of the lower edge at engagement. Bythe time the disengaged tools have been returned to their uppermostposition the upper edge of this formed section has moved down to theoriginal vertical location of the lower edge. The tools can therefore bemoved inwardly to engage a succeeding section of sheet which is adjacentthe formed section.

It will be appreciated that although in the above apparatus the tool 125on the rear platen 118 has a flat operative face this tool could haveprojecting proportions which engage the sheet as the platen approachesits operative position and forces the hot sheet into the recesses 129 inthe forward tool 128.

Further, it will be appreciated that it is not necessary for bothplatens 117 and 118 to be movable but that one could be fixedpermanently in its operative position. Such an apparatus might bearranged with the platens disposed in horizontal planes, the lowerplaten being fixed to a bedplate of the apparatus and the upper platemovable upwardly and downwardly relative thereto. Sheets of hot plasticsmaterial to be formed into articles could then be individually placed onthe lower platen rather than fed continuously from an extrusionapparatus.

I claim:

1. Apparatus for forming articles from sheet plastics materialcomprising twlo parallel arranged, relatively movable platensrespectively providing co-operating tool means adapted, when the platensare disposed in their operative positions, to form an article from asection of a sheet of hot plastics material disposed between theplatens, means for effecting relative movement of the platens towardsone another, stop means having parts which engage when the platens reachtheir operative positions and serve to retain the platens in thesepositions against the action of the moving means, cutting means fixedlysecured to one of the platens, remotely of the stop means, and soarranged that the periphery of the sheet section is engaged fromopposite sides of the sheet by the cutting means and facing parts of theother platen, respectively when the platens are in their operativepositions, and means for causing the cutting means and the said facingparts to be urged together more strongly, whereby the inherentflexibility of a platen allows further, limited relative movementbetween the cutting means and the said facing parts suflicient to causethe sheet to be out along at least a major part of the periphery of thesection.

2. Apparatus as claimed in claim 1, wherein the cutting means arefixedly secured to a tool on the said one platen with the cutting edgesthereof projecting from the tool towards the said facing parts.

3. Apparatus as claimed in claim 2, wherein the cutting means comprisecutting elements which extend along the periphery of the said tool sothat the sheet is out along the whole of the periphery of the section.

4. Apparatus as claimed in claim 3, wherein the tool means are adapted,when the platens are disposed in their operative positions, to form aplurality of articles from a section of a sheet of hot plastics materialdisposed between the platens, and the cutting means comprise furthercutting elements which extend across the said section so that, uponoperation of the cutting means the said articles are detached from thesheet and from one another.

5. Apparatus as claimed in claim 2, wherein the cutting edges of thecutting means project from the said tool through a distanceapproximately equal to one and a half times the thickness of the sheetmaterial.

6. Apparatus as claimed in claim 2, wherein the said facing parts of theother platen are pants of a tool on the said other platen.

7. Apparatus as claimed in claim 2, wherein the platens are mounted on acarriage and each platen is movable relative to the carriage towards andaway from the sheet, each platen having fixedly secured thereto a partof the stop means which engages a further part of the stop means,fixedly secured relative to the carriage, when the platen is in itsoperative position.

8. Apparatus as claimed in claim 2 for forming articles from sheetplastics material emerging from the outlet of an extruding apparatus,comprising an elongated supporting structure upon which the platens arereciprocably mounted and which, when disposed close to the outlet of theextrusion apparatus, provides a path along which the platens can bereciprocated towards and away from the said outlet, driving means fordriving material emerging from the said outlet along the path providedby the supporting structure, means for advancing the said platens, afterrelative movement thereof to operative positions in which a section ofheated material close to the said outlet is engaged by the tool means,along the said path in a direction away from the outlet and at a ratesensibly equal to the rate of supply of material therefrom, means forwithdrawing the said platens so that the tool means are disengaged fromthe sheet section after the forming of an article therefrom andoperation of the cutting means, and means for rapidly returning .theplatens along the path to their initial position for engagement of thetool means with a succeeding section of the sheet.

9. Apparatus as claimed in claim 8, wherein the supporting structure isupright and provides a vertical path down which material emerging fromthe outlet of an extrusion apparatus can be driven and along which thetool means are reciprocable.

References Cited by the Examiner UNITED STATES PATENTS 2,967,328 1/1961Shelby et a1. 18--19 3,007,201 ll/l96l Brummer l8-l9 X 3,159,698 l/1964Suh et al. 3,166,790 l/1965 Keyes 18l9 FOREIGN PATENTS 1,147,007 1l/1957France.

WILLIAM J. STEPHENSON, Primary Examiner.

1. APPARATUS FOR FORMING ARTICLES FROM SHEET PLASTIC MATERIAL COMPRISINGTWO PARALLEL ARRANGED, RELATIVELY MOVABLE PLATENS RESPECTIVELY PROVIDINGCO-OPERATING TOOL MEANS ADAPTED, WHEN THE PLATENS ARE DISPOSED IN THEIROPERATIVE POSITIONS, TO FORM AN ARTICLE FROM A SECTION OF A SHEET OF HOTPLASTICS MATERIAL DISPOSED BETWEEN THE PLATENS, MEANS FOR EFFECTINGRELATIVE MOVEMENT OF THE PLATENS TOWARD ONE ANOTHER, STOP MEANS HAVINGPARTS WHICH ENGAGE WHEN THE PLATENS REACHED THEIR OPERATIVE POSITIONSAND SERVE TO RETAIN THE PLATENS IN THESE POSITIONS AGAINST THE ACTION OFTHE MOVING MEANS, CUTTING MEANS FIXEDLY SECURED TO ONE OF THE PLATENS,REMOTELY OF THE STOP MEANS, AND SO ARRANGED THAT THE PERIPHERY OF THESHEET SECTION IS ENGAGED FROM OPPOSITE SIDES OF THE SHEET BY THE CUTTINGMEANS AND FACING PARTS OF THE OTHER PLATEN, RESPECTIVELY WHEN THEPLATENS ARE IN THEIR OPERATIVE POSITIONS, AND MEANS FOR CAUSING THECUTTING MEANS AND THE SAID FACING PARTS TO BE URGED TOGETHER MORESTRONGLY, WHEREBY THE INHERENT FLEXIBILITY OF A PLATEN ALLOWS FURTHER,LIMITED RELATIVE MOVEMENT BETWEEN THE CUTTING MEANS AND THE SAID FACINGPARTS SUFFICIENT TO CAUSE THE SHEET OF THE CUT ALONG AT LEAST MAJOR PARTOF THE PERIPHERY OF THE SECTION.